If you have problems with the tumbler flap, you should get a CEL.
However, as per my post last week, I did not, and the code only showed on the Benz diagnostics.
However, it is less then 5 min to check under the bonnet:
Remove the front part of the plastic engine cover (can lift up from it's 4 clips holding it).
Under that, you see 3 black actuators, of which the middle one operates the mechanism for the tumble flaps.
Most likely, if something is broken, it is the plastic triangular bracket.
It is all tight, but with a torch and a screwdriver, you can poke around a bit, and see if the mechanism is freely or controlled moving (without or with the actuator).
If it freely moves, and stays in the position you leave it while the engine is running, it is possible broken.
I had the bracket replaced just last week, the Indy dealer even had them in stock, very common repair.
Just check the other plastic parts inside the manifold while it is out though.
E.
PS. YouTube got plenty of info on this matter.
